{
  description = "Aria's NixOS Flake";

	nixConfig = {
		experimental-features = [ "nix-command" "flakes" ];
		substituters = [
			"https://cache.nixos.org/"
		];

		extra-substituters = [
      # Nix community's cache server
      "https://nix-community.cachix.org"
    ];
		extra-trusted-public-keys = [
      "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
    ];
	};

  # This is the standard format for flake.nix.
  # `inputs` are the dependencies of the flake,
  # and `outputs` function will return all the build results of the flake.
  # Each item in `inputs` will be passed as a parameter to
  # the `outputs` function after being pulled and built.
  inputs = {
    # There are many ways to reference flake inputs.
    # The most widely used is `github:owner/name/reference`,
    # which represents the GitHub repository URL + branch/commit-id/tag.

    # Official NixOS package source, using nixos-unstable branch here
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    # home-manager, used for managing user configuration
    home-manager = {
      url = "github:nix-community/home-manager/release-23.05";
      # The `follows` keyword in inputs is used for inheritance.
      # Here, `inputs.nixpkgs` of home-manager is kept consistent with
      # the `inputs.nixpkgs` of the current flake,
      # to avoid problems caused by different versions of nixpkgs.
      inputs.nixpkgs.follows = "nixpkgs";
    };

		neovim.url = "github:neovim/neovim/stable";
  };

  # `outputs` are all the build result of the flake.
  #
  # A flake can have many use cases and different types of outputs.
  # 
  # parameters in function `outputs` are defined in `inputs` and
  # can be referenced by their names. However, `self` is an exception,
  # this special parameter points to the `outputs` itself(self-reference)
  # 
  # The `@` syntax here is used to alias the attribute set of the
  # inputs's parameter, making it convenient to use inside the function.
  outputs = { self, nixpkgs, ... }@inputs: {
    nixosConfigurations = {
      # By default, NixOS will try to refer the nixosConfiguration with
      # its hostname, so the system named `Voyager` will use this one.
      # However, the configuration name can also be specified using:
      #   sudo nixos-rebuild switch --flake /path/to/flakes/directory#<name>
      #
      # The `nixpkgs.lib.nixosSystem` function is used to build this
      # configuration, the following attribute set is its parameter.
      #
      # Run the following command in the flake's directory to
      # deploy this configuration on any NixOS system:
      #   sudo nixos-rebuild switch --flake .#Voyager
      "Voyager" = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";

        # The Nix module system can modularize configuration,
        # improving the maintainability of configuration.
        #
        # Each parameter in the `modules` is a Nix Module, and
        # there is a partial introduction to it in the nixpkgs manual:
        #    <https://nixos.org/manual/nixpkgs/unstable/#module-system-introduction>
        # It is said to be partial because the documentation is not
        # complete, only some simple introductions.
        # such is the current state of Nix documentation...
        #
        # A Nix Module can be an attribute set, or a function that
        # returns an attribute set. By default, if a Nix Module is a
        # function, this function can only have the following parameters:
        #
        #  lib:     the nixpkgs function library, which provides many
        #             useful functions for operating Nix expressions:
        #             https://nixos.org/manual/nixpkgs/stable/#id-1.4
        #  config:  all config options of the current flake, every useful
        #  options: all options defined in all NixOS Modules
        #             in the current flake
        #  pkgs:   a collection of all packages defined in nixpkgs,
        #            plus a set of functions related to packaging.
        #            you can assume its default value is
        #            `nixpkgs.legacyPackages."${system}"` for now.
        #            can be customed by `nixpkgs.pkgs` option
        #  modulesPath: the default path of nixpkgs's modules folder,
        #               used to import some extra modules from nixpkgs.
        #               this parameter is rarely used,
        #               you can ignore it for now.
        #
        # Only these parameters can be passed by default.
        # If you need to pass other parameters,
        # you must use `specialArgs` by uncomment the following line:
        #
        # specialArgs = {...}  # pass custom arguments into all sub module.
        modules = [
          # Import the configuration.nix here, so that the
          # old configuration file can still take effect.
          # Note: configuration.nix itself is also a Nix Module,
          ./configuration.nix
        ];
      };
    };
  };
}